package tools
{
    import flash.display.BitmapData;
    import flash.display.BlendMode;
    import flash.display.DisplayObject;
    import flash.display.Sprite;
    import flash.geom.ColorTransform;
    import flash.geom.Matrix;
    import flash.geom.Point;
    import flash.geom.Rectangle;
    
    /**
     * 高级碰撞检测
     * @see http://www.tink.ws/blog/as-30-hittest/
     */
    public class HitTest
    {
        
        public static function complexHitTestObject(target1:DisplayObject, target2:DisplayObject, accurracy:Number = 1):Boolean
        {
            return complexIntersectionRectangle(target1, target2, accurracy).width != 0;
        }
        
        public static function intersectionRectangle(target1:DisplayObject, target2:DisplayObject):Rectangle
        {
            // If either of the items don't have a reference to stage, then they are not in a display list
            // or if a simple hitTestObject is false, they cannot be intersecting.
            if (!target1.root || !target2.root || !target1.hitTestObject(target2))
            {
                return new Rectangle();
            }
            
            // Get the bounds of each DisplayObject.
            var bounds1:Rectangle = target1.getBounds(target1.root);
            var bounds2:Rectangle = target2.getBounds(target2.root);
            
            // Determine test area boundaries.
            var intersection:Rectangle = new Rectangle();
            intersection.x = Math.max(bounds1.x, bounds2.x);
            intersection.y = Math.max(bounds1.y, bounds2.y);
            intersection.width = Math.min((bounds1.x + bounds1.width) - intersection.x, (bounds2.x + bounds2.width) - intersection.x);
            intersection.height = Math.min((bounds1.y + bounds1.height) - intersection.y, (bounds2.y + bounds2.height) - intersection.y);
            
            return intersection;
        }
        
        public static function complexIntersectionRectangle(target1:DisplayObject, target2:DisplayObject, accurracy:Number = 1):Rectangle
        {
            if (accurracy <= 0)
                throw new Error("ArgumentError: Error #5001: Invalid value for accurracy", 5001);
            
            // If a simple hitTestObject is false, they cannot be intersecting.
            if (!target1.hitTestObject(target2))
            {
                return new Rectangle();
            }
            
            var hitRectangle:Rectangle = intersectionRectangle(target1, target2);
            // If their boundaries are no interesecting, they cannot be intersecting.
            if (hitRectangle.width * accurracy < 1 || hitRectangle.height * accurracy < 1)
            {
                return new Rectangle();
            }
            var bitmapData:BitmapData = new BitmapData(hitRectangle.width * accurracy, hitRectangle.height * accurracy, false, 0x000000);
            
            // Draw the first target.
            bitmapData.draw(target1, HitTest.getDrawMatrix(target1, hitRectangle, accurracy), new ColorTransform(1, 1, 1, 1, 255, -255, -255, 255));
            // Overlay the second target.
            bitmapData.draw(target2, HitTest.getDrawMatrix(target2, hitRectangle, accurracy), new ColorTransform(1, 1, 1, 1, 255, 255, 255, 255), BlendMode.DIFFERENCE);
            
            // Find the intersection.
            var intersection:Rectangle = bitmapData.getColorBoundsRect(0xFFFFFFFF, 0xFF00FFFF);
            
            bitmapData.dispose();
            
            // Alter width and positions to compensate for accurracy
            if (accurracy != 1)
            {
                intersection.x /= accurracy;
                intersection.y /= accurracy;
                intersection.width /= accurracy;
                intersection.height /= accurracy;
            }
            
            intersection.x += hitRectangle.x;
            intersection.y += hitRectangle.y;
            
            return intersection;
        }
        
        
        protected static function getDrawMatrix(target:DisplayObject, hitRectangle:Rectangle, accurracy:Number):Matrix
        {
            var localToGlobal:Point;
            
            var matrix:Matrix;
            
            var rootConcatenatedMatrix:Matrix = target.root.transform.concatenatedMatrix;
            
            localToGlobal = target.localToGlobal(new Point());
            matrix = target.transform.concatenatedMatrix;
            matrix.tx = localToGlobal.x - hitRectangle.x;
            matrix.ty = localToGlobal.y - hitRectangle.y;
            
            matrix.a = matrix.a / rootConcatenatedMatrix.a;
            matrix.d = matrix.d / rootConcatenatedMatrix.d;
            if (accurracy != 1)
            {
                matrix.scale(accurracy, accurracy);
            }
            
            return matrix;
        }
    
    }

}